56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
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/* mgf1.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2010 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include <string.h>
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#include "mgf1.h"
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#include "hfal-basic.h"
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/*
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* MGF1 as defined in PKCS #1 v2.1 B.2.1
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*/
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void mgf1_short_seed(void* dest, const void* seed, uint8_t seed_len_B, uint16_t out_length_B, const mgf1_parameter_t* p){
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uint8_t buffer[seed_len_B+4];
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uint32_t counter=1;
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uint8_t hv_len = hfal_hash_getHashsize(p->hashfunction)/8;
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memcpy(buffer, seed, seed_len_B);
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memset(buffer + seed_len_B, 0, 4);
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while(out_length_B >= hv_len){
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hfal_hash_mem(p->hashfunction, dest, buffer, (seed_len_B + 4) * 8);
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dest = (uint8_t*)dest + hv_len;
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out_length_B -= hv_len;
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buffer[seed_len_B + 3] = counter & 0xff;
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buffer[seed_len_B + 2] = (counter>>8) & 0xff;
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buffer[seed_len_B + 1] = (counter>>16) & 0xff;
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buffer[seed_len_B + 0] = (counter>>24) & 0xff;
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++counter;
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}
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if(out_length_B){
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uint8_t hash_buffer[hv_len];
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hfal_hash_mem(p->hashfunction, hash_buffer, buffer, (seed_len_B + 4) * 8);
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memcpy(dest, hash_buffer, out_length_B);
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}
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}
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void mgf1(void* dest, const void* seed, uint16_t seed_len_B, uint16_t out_length_B, const mgf1_parameter_t* p){
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mgf1_short_seed(dest, seed, seed_len_B, out_length_B, p);
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}
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